Effetti del rame sulla carta. Il caso paticolare della degradazione di un libro sardo del settecento

While the degrading effects of iron sulphate (green vitriol) on paper documents have been the subject of several archaeometric studies, owing to its presence in almost all the ancient ink recipes, much less is known about the degradation brought about by copper sulphate. The presence of this inorganic compound (blue vitriol) is generally associated with iron, making it difficult to evaluate its specific degradation path. In this paper we present the results of the FTIR analysis of a brittle and discoloured XVIII Century book which shows a strong copper-induced degradation. As in the case of iron, copper produces a relevant amount of oxalates at the expense of amorphous regions of cellulose and leaves several carboxyl groups on the remainder crystalline fraction.